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granard
30th Jun 2011, 20:56
Has the FAA introduced a new rule for multiengine aircraft so they can't go further than 180 minutes from an alternate airport.

grounded27
1st Jul 2011, 00:28
Knew it was coming, ETOPS will affect all aircraft despite the twin in the abbreviation.

ECAM_Actions
1st Jul 2011, 00:45
On the face of it, that seems utterly ridiculous.

What is the rationale for this decision? Who does it affect: all traffic originating from US airspace or any aircraft operating anywhere where the airline is US based?

aterpster
1st Jul 2011, 00:47
The OP asked a question rather than making a comment. He just forgot the question mark.

john_tullamarine
1st Jul 2011, 01:51
Knew it was coming, ETOPS will affect all aircraft despite the twin in the abbreviation

One needs to look at the history.

Pre-ETOPS, the design/operating standards required that multi-engine aircraft be able to meet certain performance standards with two failed engines else they were restricted by the 90 minute rule.

Clearly this affected all twins but, also, restricted some 3/4 engined machines.

As the reliability of engines improved, we saw the introduction of (progressively longer) ETOPS operations by the larger twins.

As engine and systems reliability has improved over the years, the concern, for some years, has been less with the (number of) engines and more with other systems considerations - ergo, the number of engines is now largely irrelevant, with the concern being more along the lines of "if we are a LONG, LONG way from a safe haven, how are we placed if this, that, or the other circumstance might occur ?"

It might be better to replace ETOPS with something like "operations remote from suitable aerodromes" and move away from a concern specifically directed towards the number of engines.

Turbine D
1st Jul 2011, 02:10
JT,

I think a lot of this has to do with diversion planning as related to route planning. It places more onus on the planners to assure airports which can accept large 3 or 4 engine airliners are along the route and within the 180 minute limit.

aterpster
1st Jul 2011, 02:22
j.t.:

One needs to look at the history.

Pre-ETOPS, the design/operating standards required that multi-engine aircraft be able to meet certain performance standards with two failed engines else they were restricted by the 90 minute rule.

Clearly this affected all twins but, also, restricted some 3/4 engined machines.

John,

Pre-ETOPS, twins couldn't make "crossings."

As I recall with 3 or 4 engine birds, we had to turn around under circumstances.

grounded27
1st Jul 2011, 02:37
Ahh, 180min with extension is not a big deal. 3 and 4 engine aircraft will not be as restricted having more redundant systems anyways. To the question above, as far as I know being in the US it will apply to FAA reg acft, expect the world to follow or be onboard. 180 ETOPS is more a burdon on MX... But there will be less rules as negociated with the CAA as there are redundant systems a twin can not provide.

john_tullamarine
1st Jul 2011, 03:19
TD & A,

Indeed, the extant operational problems are the day to day drivers. However, the two-engine out cruise capability driver in concert with the restrictive 90 minute rule started the gameplay originally.

grounded27
1st Jul 2011, 04:02
Yeah, J.T. , hope you would agree that the 180 minute rule will not harm most segments, hell for those that they do they will only build more airstrips... Correction, lengthen runways, creating more jobs.


Edit.. Back to the days that Pan Am built airports. "If you build it they will come" may be a good thing, pioneering once again!

galaxy flyer
1st Jul 2011, 06:56
Utterly ridiculous, the FAA has no knowledge or concern for 3 and 4 engine operations. They are trying to fit everything into their narrow 2-engine view. While ETOPS experience has made ALL airliners, regardless of engines, more reliable and safer, there is no reason to restrict 3 and 4 engine airliners to having 180 minute ERAs. A 747 OEI has more redundancy than a B777 takes off with.

lomapaseo
1st Jul 2011, 13:35
Engines are not redundant when you run into ice crystals, dirty fuel, ash, or quik chk maint. that forgets to put the caps back on the oil tanks or borescope or even when an engine blows up on one side and sheds its parts into its neighbor.

galaxy flyer
4th Jul 2011, 02:01
Yes, lomapaseo

But, if any of those events happen, it doesn't matter how many engines the plane has. A four-engine plane is a very different beast the the twins and twin operations rules should NOT be applied to them. The FAA is showing its lack of knowledge and experience in restricting quads. But, then again, they might just be in the pocket of Mr. Boeing and Company.

GF

lomapaseo
4th Jul 2011, 14:26
But, if any of those events happen, it doesn't matter how many engines the plane has. A four-engine plane is a very different beast the the twins and twin operations rules should NOT be applied to them. The FAA is showing its lack of knowledge and experience in restricting quads. But, then again, they might just be in the pocket of Mr. Boeing and Company.

GF

"A very different beast" :confused:

Yes, 2 vs 4 .

Yes, both certified to fly with a single engine out. Both in need of a diversion with two engines out. And the one with more engines has a greater chance of independent failure combinations, not to mention the myriad of risks having nothing to do with muliple engines out.

I never thought of this as a Boeing or Airbus design issue because it hurts my brain to figure out why it is good or bad.

I deal with historical data and safety analysis.

But in the greater sphere of things it's small change in contribution to overall risk, so I only get into this fray for fun :)

aterpster
4th Jul 2011, 15:09
Lamapaseo:
Yes, 2 vs 4 .

Yes, both certified to fly with a single engine out. Both in need of a diversion with two engines out. And the one with more engines has a greater chance of independent failure combinations, not to mention the myriad of risks having nothing to do with muliple engines out.
No, the twin doesn't because it's going into the drink.

The four engine aircraft has a greater chance of an engine failure and thus a turn around fairly early in the flight. But, that chance is very small. Once you get far out the 4 engine aircraft is simply safer than the two engine aircraft, but the economics are not as good. So, ETOPS is all about money.

The greater chance of an engine failure "early on" in a 4-engine bird is an "insurance payment" for greater safety when out somewhere in the middle, more or less.

ECAM_Actions
4th Jul 2011, 15:10
Assuming the engines to be perfectly reliable (100% reliability no matter the conditions), what is left on the aircraft that is now more of a factor in terms of adversely affecting safety?

Put another way, of ALL diverts of aircraft flying hours away from the nearest suitable, how many were due to something NOT engine related?

Any figures?

EDIT to add:

The greater chance of an engine failure "early on" in a 4-engine bird is an "insurance payment" for greater safety when out somewhere in the middle, more or less.
Agreed that more engines increases the risk of an engine failure, but what is the chance of a 4 engine suffering dual-engine failure compared with a twin suffering dual-engine failure?

john_tullamarine
4th Jul 2011, 15:46
Assuming the engines to be perfectly reliable (100% reliability no matter the conditions),

With such an assumption then we can presume that folks will fly in single engined airliners - why waste all that money on more than one really needs ?

Put another way, of ALL diverts of aircraft flying hours away from the nearest suitable, how many were due to something NOT engine related?

Don't have any figures to hand. However, systems other than engines are the driving concern in recent years - multiple electrical failures, on board fire are but two which spring to mind.

what is the chance of a 4 engine suffering dual-engine failure compared with a twin suffering dual-engine failure?

Somewhat higher, I suggest - two engines are on the same side. If one lets go in a big way, there is a rather higher probability that debris will take out the adjacent engine rather than (the) one on the other side. Plently of examples around to back up that thought.

ECAM_Actions
4th Jul 2011, 16:37
Assuming the engines to be perfectly reliable (100% reliability no matter the conditions),

With such an assumption then we can presume that folks will fly in single engined airliners - why waste all that money on more than one really needs ?It was hypothetical. :) In other words, if the engines are removed as a concern, then what is next? You addressed this though in your next part of your reply.

Put another way, of ALL diverts of aircraft flying hours away from the nearest suitable, how many were due to something NOT engine related?

Don't have any figures to hand. However, systems other than engines are the driving concern in recent years - multiple electrical failures, on board fire are but two which spring to mind.Fire is a strange one; it is thought in a lot of cases they couldn't reach the surface in time even if the airport was ideally located (e.g. Swissair Flight 111).

what is the chance of a 4 engine suffering dual-engine failure compared with a twin suffering dual-engine failure?

Somewhat higher, I suggest - two engines are on the same side. If one lets go in a big way, there is a rather higher probability that debris will take out the adjacent engine rather than (the) one on the other side. Plenty of examples around to back up that thought.That is a good point. Even the Qantas A380 ended up being unable to control #1 after the #2 let go, despite #1 itself being undamaged.

john_tullamarine
4th Jul 2011, 16:58
It was hypothetical.

.. as was my tongue-in-cheek response ..

Pontius Navigator
4th Jul 2011, 17:20
Fire is a strange one; it is thought in a lot of cases they couldn't reach the surface in time even if the airport was ideally located (e.g. Swissair Flight 111).[/i]

There were three Nimrods, one made it, one ditched and one didn't.

OK not a modern design and based on the Comet but in each case the time from fire to catastrophe was extremely short. Of the one that landed and the one that ditched, neither was at a normal transit altitude when the emergency occurred.

aviatorhi
4th Jul 2011, 23:40
I recall reading about this (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/2e0f31985abd83ef8625746b0057fd06/$FILE/AC%20120-42B.pdf) a while back; my understanding it that any amount of engines with pax on board requires the flight to be conducted under ETOPS (ExTended range OPerationS). Freight with 3 or more engines does not require it.

Turbine D
5th Jul 2011, 03:27
GF,

Utterly ridiculous, the FAA has no knowledge or concern for 3 and 4 engine operations. They are trying to fit everything into their narrow 2-engine view. While ETOPS experience has made ALL airliners, regardless of engines, more reliable and safer, there is no reason to restrict 3 and 4 engine airliners to having 180 minute ERAs. A 747 OEI has more redundancy than a B777 takes off with.

Not necessarily true. Tis a fact, when it comes to engines, those on two engine ETOPS aircraft demonstrate a better record having less in-flight shutdowns or failures compared to engines on three or four engine aircraft. Some of this is advancement in engine technology but some is due to the extra requirements of engine maintenance and monitoring required to gain a 180 minute ETOPS rating. Engines are only part of the reasons for ETOPS. Other reasons for diversions include decompression, medical emergencies, observed smoke in the cabin or fire indication in the cargo hold. In twenty years, 1980-2000, 33 of 73 cruise decompressions occurred on airplanes with more than two engines. Diversion rate for aircraft causes or non-aircraft causes are the same for 2, 3 or 4 engine aircraft.

180 minute ETOPS approval starts with the airline meeting requirements of maintenance, training of ground personnel and flight personnel, training of route planners with an emphasis on suitable diversion airport for the aircraft requiring a diversion. This planning includes requirements to carry extra fuel for diversion purposes.

So it is more than just engines and when you think of it, how many routes in the world traveled by 3 or 4 engine aircraft would be affected by a 180 minute ETOPS requirement?

TD

aterpster
5th Jul 2011, 11:18
ETOPS originally meant Extended Twin Operations. But, the FAA is ever "creative."

It has been known to mean Engines Turn or Passengers Swim.

Pontius Navigator
5th Jul 2011, 21:32
Tis a fact, when it comes to engines, those on two engine ETOPS aircraft demonstrate a better record having less in-flight shutdowns or failures compared to engines on three or four engine aircraft.

Is it not possible that a pilot is more willing to shut down 25% of his power plants than one where it would be 50%?

lomapaseo
5th Jul 2011, 21:51
Is it not possible that a pilot is more willing to shut down 25% of his power plants than one where it would be 50%?

Yes

Which brings up the terms of "hard" vs "soft" shutdown.
which make it even harder to sort out real risk from subjective risk.

Desert185
5th Jul 2011, 23:27
I've had three shutdowns on four-engine airplanes.

1. KONT-PHNL: Turbine failure, shutdown, dump, return to departure airport.

2. PANC-RJAA: Slow loss of oil, have lunch and monitor, low oil pressure light confirmed by OP gauge, shutdown and continue 1.5 hrs to destination. Pinhole leak in oil line.

3. RCTP-RJAA: Loss of oil pressure after takeoff by 10,000', shutdown, continue to destination. Oil tank cap missing.

If flying a two-engine airplane, situation one would be no change, situation two would have been a diversion to an Aleutian chain airport and situation three would have been an immediate landing back at departure airport.

A four-engine airplane gives you more options, including continuing to destination for all the obvious reasons. The other thing to consider with a two-engine airplane besides ETOPS requirements is terrain enroute should an engine fail. Our two-holers had to fly different, more lengthy routes on some sectors than our four-engine airplanes.

I know I'm prejudiced, but I would much rather operate a four-engine airplane (and have since 1977) for the reasons outlined.

Edit: One also has the option of a three-engine ferry to a more capable maintenance base, which is not an option with a two-engine airplane.

galaxy flyer
5th Jul 2011, 23:45
Desert185

Agreed, I cannot make an argument that tris and quads are statistically safer (there isn't one), but they do offer more options and possibilities. One of which has been, and should remain, operations beyond any enroute alternate airports. Yes, trans-polar flights can be done in either plane, but I'd much rather shutdown an engine at 90N and be able to continue into Fairbanks than do so and be forced into Thule or Barrow or a Russian airport in winter.

GF

avgenie
8th Jul 2011, 06:39
I believe the FAA must ensure that all airplanes on commercial operations whether twins, tris or quads are equally safe.

It appears we are fixated on the number of engines and the flexibility they offer when an engine fails.

Based on what I have read, it is my understanding that ETOPS covers more than engine issues.

I understand the FAA could not ignore the issue of tris/quads decompression enroute long-range operations and the resulting need for additional fuel reserves. (Remember Qantas 747 decompression and Manila diversion, luckily the incident happened close to an airport, imagine the same scenario on Sydney-Santiago!!)

I believe, similar to ETOPS for twins, ETOPS for tris /quads will require fuel planning for such eventuality (decompression). Airlines can address this by carrying additional fuel. If they do not want to carry additional fuel and forgo the payload then they will have to look for a suitable alternates enroute. Based on the limited knowledge I have on ETOPS, it appears to me that ETOPS greatly enhances the overall safety of all operations including those of tris & quads.

aterpster
8th Jul 2011, 10:06
It seems it got redefined in 2007:

ETOPS - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/ETOPS)

BOAC
8th Jul 2011, 10:53
I seem to recall it being discussed here then - I think it was being called LROPS at the time. EOPS is a bit of a mouthful!

Spooky 2
8th Jul 2011, 21:21
Maybe it's been said here before but I didn't see it. ETOPS for Tri and Quads are appicable to operations in excess of 180 minutes. This does not apply to cargo operations, just pax. Mostly in place for Polar Ops and maybe a few South Pacific routings. These Tri and Quad ETOPS do not exactly mirror Twin ETOPS so it is not a one size fits all template.

aterpster
9th Jul 2011, 02:05
Spooky 2:

Maybe it's been said here before but I didn't see it. ETOPS for Tri and Quads are appicable to operations in excess of 180 minutes. This does not apply to cargo operations, just pax. Mostly in place for Polar Ops and maybe a few South Pacific routings. These Tri and Quad ETOPS do not exactly mirror Twin ETOPS so it is not a one size fits all template.

Check the link in my Post #31.

galaxy flyer
9th Jul 2011, 02:31
avgenie

Quads have to flight plan accounting for depressurization at the ETP, so it shouldn't be an issue. I agree ETOPS has, and will, improve reliability and safety for quads--better fire suppression, ETOPS=qualified engines and accessories, avionics cooling, etc. But, since twins HAVE to land at the nearest suitable airport in the event of engine failure, why are we extending that restriction to quads? They have demonstrated many times, that if planned correctly, can safety continue after an engine failure to the destination or a better alternate, esp. on trans-polar, trans-Siberian, and some oceanic routes.

GF

Desert185
9th Jul 2011, 04:44
avgenie says:

I believe, similar to ETOPS for twins, ETOPS for tris /quads will require fuel planning for such eventuality (decompression). Airlines can address this by carrying additional fuel. If they do not want to carry additional fuel and forgo the payload then they will have to look for a suitable alternates enroute. Based on the limited knowledge I have on ETOPS, it appears to me that ETOPS greatly enhances the overall safety of all operations including those of tris & quads.


The present rules for three and four-engine overwater operations, taking into account three and two-engine ETP's, provides all the safety one needs without applying the imagined "safety enhancements" of ETOPS.

avgenie
10th Jul 2011, 03:31
galaxy flyer
Quads have to flight plan accounting for depressurization at the ETP, so it shouldn't be an issue. I agree ETOPS has, and will, improve reliability and safety for quads--better fire suppression, ETOPS=qualified engines and accessories, avionics cooling, etc. But, since twins HAVE to land at the nearest suitable airport in the event of engine failure, why are we extending that restriction to quads? They have demonstrated many times, that if planned correctly, can safety continue after an engine failure to the destination or a better alternate, esp. on trans-polar, trans-Siberian, and some oceanic routes.
I am not sure if most of the airlines consider depressurization at the ETP. I am under the impression that ETP fuel is calculated based on an engine out. So most of the flight plans for A340/747/A380 would be based around 20, 000 ft (1 eng inop level off) rather than 10, 000 ft. (typical depressurization altitude unless extra oxygen).

galaxy flyer
10th Jul 2011, 03:58
Are you contending that air carriers can plan oceanic crossing with a "wet footprint" in the event of depressurization? I doubt that.

GF

aterpster
10th Jul 2011, 11:40
gf:

Are you contending that air carriers can plan oceanic crossing with a "wet footprint" in the event of depressurization? I doubt that.

Without a wet footprint would be much more desirable.:)

I can only speak of my limited experience in this reqard. I never flew International but I had a few years of flying the L-1011 from LAX to Honolulu, which is a very long over-water segment. San Francisco and Hilo were our deversionary alternates unless a problem happened with 300 miles of departure or arrival.

In the event of a loss of pressurization at the ETP we could indeed make Hilo or San Francisco at 10,000 feet without risk of a wet footprint. Or, we could make Hilo or San Francisco with the loss of one engine, whether we had pressurization or not. The diversion at the ETP saved about 200 miles, which is a fair about of extra fuel.